Adjustable golf club with hydrodynamic lock-up

ABSTRACT

The various embodiments of the invention are directed to a golf club head having an adjustable loft, wherein the loft angle is hydrodynamically locked during impact of the club head with the ball.

FIELD OF THE INVENTION

The present invention relates to golf clubs, and more particularlyrelates to a golf club head having an adjustable loft.

BACKGROUND OF THE INVENTION

In golf, clubs are used having varying loft angles to impart greater orlesser distance or height to the ball. Drivers having a slight anglefrom the vertical are used to drive the ball a great distancehorizontally with a relatively flat trajectory. A putter with virtuallyno loft angle is used on the green itself. At intermediate distances,irons having varying loft angles measured from the vertical are used.Typically, larger loft angles are used for shorter distances. Mostgolfers use up to 14 clubs (limited by rule) with varying lofts atapproximately four-degree increments. The need for multiple clubscreates a number of disadvantages, such as the high cost of a completeor partial set, and the need for transportation of a bulky and heavy setof clubs, both to and on the course.

A number of adjustable golf clubs have been developed with the object ofreducing the number of clubs required. Many designs have used one ormore sets of teeth or splines to key-in the various desired loft angles.Adjustable club heads using splined shafts are exemplified by U.S. Pat.Nos. 1,219,417 to Vories; 2,305,270 to Nilson; 1,429,569 to Craig;2,571,970 to Verderber; 3,601,399 to Agens et al; and 4,878,666 toHosoda. Clubs employing multiple toothed rings for vernier adjustmentare exemplified by U.S. Pat. Nos. 2,882,053 to Lorthiois; and 3,840,231and 5,538,245, both to Moore. A ratcheting vernier adjustment is taughtin U.S. Pat. No. 5,133,553 to Divnick. Sealed containers havingpermeable elastomeric sheets sealed together and inflated with a gashaving low permeability therethrough is taught in U.S. Pat. No.4,287,250, to Rudy. The teachings of the patents cited above areentirely incorporated herein by reference.

As the impact of the club head with the ball generates large forces andtorques acting in unpredictable directions, various auxiliary fasteningdevices such as nuts, screws and levers have been used to lock-up thehead so that the loft angle does not accidentally change during use.These auxiliary devices are undesirable, as they detract from theenjoyment of the game. They are also prone to failure with repeated use,due to over or under tightening, and to contamination or corrosion.

It would be desirable for a club to be self-locking, so that noauxiliary devices would be needed. It would also be desirable that theconcentration of the golfer not be broken by the need to makecomplicated adjustments to the club. And it would be most desirable thatthe loft angle be changeable in one continuous and smooth motion by thegolfer.

SUMMARY OF THE INVENTION

The present invention provides a uniquely simple solution to theproblems associated with adjustable golf clubs, and does so withoutrequiring that the golfer remember arcane and complicated adjustmentprocedures. Rather, the instant invention provides a perfectly naturaland aesthetically desirable look and feel for both the club and theadjustment thereof, while also enhancing the technical performance ofthe club.

An important feature of an adjustable club is that the loft angle, onceset, does not change during use. First of all, if the equipment is notreliable, the player's lack of confidence can negatively effect hisgame, and secondly, a club head that moves under impact conditions candamage the adjustment mechanism, and ruin the club. In the presentinvention, the head, once set at the desired loft angle, ishydrodynamicly locked-up, and cannot move into an unlocked position dueto the collision of the club with a ball. This lock-up is achievedautomatically during impact conditions.

As golf is an aesthetic game, it is important that the head adjustssmoothly, substantially without noise or snap-back, and withoutrequiring tools. It is also important that the adjustment is easilyachieved without the need for calculation on the part of the golfer.

The present invention accomplishes the above and other objectives bydividing the working volume within the adjustable club head into atleast three chambers: first and second chambers filled with anincompressible fluid, and a third chamber filled with a compressiblefluid.

The working volume within the club head comprises a splined (toothed)pivot shaft which mates with a splined inner cylinder surface fixedwithin the adjustable club head. It is desirable that both the exteriorsplined surface of the pivot shaft and the interior splined surface ofthe cylinder are segmented, with gaps therebetween, so as to reduce thetotal axial motion required to de-couple the splines while providingsufficient tooth area to resist rotation. When not being adjusted, thesplines are aligned so as to prevent relative rotation, and the pressureof the gaseous fluid within the third chamber maintains this coupledaxial alignment. The third chamber pressurizes the second liquid filledchambers by means of a flexible diaphragm or floating pistontherebetween. The first chamber is pressurized by means of a fluidconduit between the first and second chambers, so that, at rest, thepressures in all three chambers are equal (and above atmospheric). Mosttypically, all chambers are coaxial with the pivot shaft, with thesecond chamber between the first and third chambers.

The conduit between the first and second chambers restricts the rate offluid flow between them. This results in a small pressure build-upwithin the first chamber relative to the second, resulting in aresistance and a smooth axial motion of the club head on the pivot shaftas the two are pressed together by the golfer during adjustment. Duringa stroke, while under impact conditions, the pressure build-up is muchgreater than it is during adjustment, and tends to resist axial motionand the resultant de-coupling of the splines. By way of example only,and not limitation, if one pound of force applied for one second isnecessary to de-couple the splines during adjustment (this is thehydrodynamic force generated by fluid flow in the conduit only, andneglects the gas pressure in the third chamber, which must also beovercome), then, during an impact of the golf head with a ball lastingonly one millisecond, a million pounds of force would be required tomove the fluid through the conduit and thereby de-couple the splines.The force required is so much greater because the hydraulic forcegenerated varies inversely with the square of the time period involved.If the impact period is three orders of magnitude smaller than theadjustment period, then the de-coupling force required will be sixorders of magnitude greater. This force resisting de-coupling is solarge that the head remains effectively locked-up during the briefperiod of impact.

BRIEF DESCRIPTION OF THE DRAWINGS

The above as well as other objects of the invention will become moreapparent from the following detailed description of the preferredembodiments of the invention, when taken together with the accompanyingdrawings in which:

FIG. 1 is a cross-sectional exploded view of a pivot cartridge showingthe various elements of one embodiment of the invention.

FIG. 2A is a cross-sectional view of an assembled pivot cartridgeaccording to an embodiment of the invention, with the cartridge in thedistal or engaged position.

FIG. 2B is a cross-sectional view of an assembled pivot cartridge as inFIG. 2A, with the cartridge in the proximal or disengaged position.

FIG. 3 is a cross-sectional view of an assembled adjustable headcomprising a pivot cartridge according to a preferred embodiment of theinvention, with the head in the distal position.

FIG. 4A is a partial cross-sectional view of an assembled adjustablehead according to an alternative embodiment of the invention, wherein afluid cell is substituted for the piston of FIG. 3.

FIG. 4B is a partial cross-sectional view of an assembled adjustablehead according to an alternative embodiment of the invention, wherein adiaphragm is substituted for the fluid cell of FIG. 4A.

FIG. 4C is a partial cross-sectional view of an assembled adjustablehead according to an alternative embodiment of the invention, wherein aspring is substituted for or supplements the compressed fluid of FIG. 3.

FIG. 5 is a cross-sectional view of an assembled adjustable headaccording to an embodiment of the invention.

FIG. 6A is a partial cross-sectional view of an assembled adjustablehead according to another embodiment of the invention, shown in thedistal orientation, and wherein the hosel is integrated into the pivotshaft.

FIG. 6B is a partial cross-sectional view of the assembled adjustablehead of FIG. 6A, shown in the proximal orientation.

FIG. 7 is a cross-sectional view of an assembled adjustable headaccording to another embodiment of the invention, with the head in thedistal position.

FIG. 8 is a right side view of the adjustable head shown in FIG. 7.

DESCRIPTION OF THE INVENTION

An exploded view of a pivot cartridge for insertion into an adjustableclub head according to a preferred embodiment of the instant inventionis shown generally as numeral 3 in FIG. 1, and the assembled pivotcartridge is shown in the engaged (distal) position generally as numeral1 in FIG. 2A and in the disengaged (proximal) position generally asnumeral 1′ in FIG. 2B. Referring now to FIGS. 1, 2A, 2B, the pivot shaft11, comprises a bearing surface 10 and a shaft extension 16. A pluralityof exterior spline (toothed) segments 12 are spaced apart by exteriorgap segments 14. A splined shaft 8 and threaded shaft extension 6 areprovided for attachment with a hosel (not shown). The pivot shaft 11mates with cylinder 30, comprising a bearing surface 22, having adiameter slightly larger than the diameter of the bearing surface 10 ofthe pivot shaft 11. Interior spline segments 24 engage exterior splinesegments 12 when in the engaged position illustrated in FIG. 2A. Abushing 31 has a bushing ID 33 for press fitting or otherwise attachingto shaft extension 16, and a bushing OD 32, slightly smaller than thediameter of the bearing surface 28 of the cylinder 30, so that it mayfreely rotate and slide therein. A seal 18 fits into groove 20 ofcylinder 30, and prevents fluid leakage from between the mating bearingsurfaces 22, 10. Piston 60 having seal 64 fitting into groove 62 floatsin bearing surface 28. Tapered hole 66 is plugged by tapered pin 68.Seal 17 fits in the groove 27 of the exterior surface of the cylinder30.

In FIG. 2A, chamber 100 constitutes the first chamber, which is filledwith a substantially incompressible fluid. This incompressible fluid maybe any liquid or gel; but oil or grease are preferred, due to thelubricating action and prevention of corrosion of the internalcomponents of the cartridge. In FIG. 2A, the pivot cartridge 1 is in theengaged (distal) position, while the pivot cartridge 1′, shown in FIG.2B, is in the disengaged (proximal) position. (“Distal” and “proximal”refer to the relative position of the club head with inserted pivotcartridge, to the hosel.) In FIG. 2B, fluid has been driven from thechamber 100 of FIG. 2A through the engaged interior and exterior splinesegments 24, 12, which together constitute a restricted conduit, tochamber 102. If the bushing OD 32 is larger or equal to the diameter ofthe bearing surface 10, chamber 102 constitutes the second chamber. Ifthe bushing OD 32 is smaller than the diameter of the bearing surface10, then fluid is also forced between the mating surfaces of the bushingOD 32 and the bearing surface 28 (a restricted conduit in series withthe engaged interior and exterior spline segments) into chamber 106,which then constitutes the second chamber. In moving between the distalto the proximal positions, the fluid pressure in the first chamberincreases by an amount which is generally proportional to the square ofthe rate of movement, and this increased pressure acts to resist themotion of the pivot shaft 11 relative to the cylinder 30. The primarypurpose of chamber 106 is to provide volumetric compliance for thechanging volume of the first chamber during motion. The first and secondchambers and restricted conduit(s), i.e., the volume bounded by seals18, 64, may be filled with an incompressible fluid by immersing theassembled cartridge 1 (sans piston 60) in the fluid and drawing andreleasing a vacuum. The piston 60 may then be inserted so that airescapes through tapered hole 66, which is then sealed with tapered pin68. Other means such as screws may be used to seal the hole 66, and thepiston 60 may be also be installed under vacuum so that no hole isnecessary.

Turning now to FIG. 3, the club head, generally indicated by numeral200, comprises the pivot cartridge 1, shown inserted in the engaged ordistal position into the club support 13, which supports club face 7.The pivot cartridge 1 is shown mounted to hosel 4 by means of nut 2.Hosel 4 is the interface to handle shaft 5, by which the club is grippedand swung. Chamber 104, formed by the piston 60, the bearing surface 28and the blind hole 108, is filled with a compressible fluid, preferablya gas or gas and liquid and/or gel mixture. This compressible fluid maybe compressed and trapped during the installation of the pivot cartridge1, as it is preferably press-fit into the blind hole 108. Thecompression of this fluid may be regulated by the position of the seal17 along the cylinder 30, with excess fluid vented by means of groove109 until the seal 17 makes contact with the open end of the blind hole108, at which point further leakage is prevented. Knurled surface 23 isprovided on the exterior of cylinder 30 to prevent rotation of thecylinder 30 within the blind hole 108. A heavy press fit, adhesives,pins, keys or brazing may also be used to prevent rotation. Insertion isfacilitated by the prior assembly of the pivot cartridge 1.

Turning now to FIG. 4A, wherein the club head is generally indicated bynumeral 201, an alternative configuration of the third chambercontaining the compressible fluid is shown as fluid cell 35, whichcomprises a hollow flexible. Fluid cell 35 may comprise polymeric,elastomeric, rubber or other flexible materials resistant to theincompressible fluid and substantially impermeable to the compressiblefluid. The fluid in the fluid cell 35 may be compressed during insertionof the pivot cartridge 1 in the same way as described above withreference to FIG. 3. While the compressible fluid may consist entirelyof air, or of gases such as nitrogen, oxygen, argon, methane, ethane,propane, butane, fluoroform, neo-pentane, and others, there areadvantages that accrue from using gases having intrinsically lowdiffusion rates due to large size and symmetrical molecular shape. Useof such gases would be especially valuable when used within a fluid cellcomprised of rubber, elastomer, or polymer. Such gases would includeperfluoropentane, perfluorohexane, perfluoroheptane,octafluorocyclobutane, perfluorocyclobutane, hexafluoropropylene,tetrafluoromethane, monochloropentafluoroethane,1,2-dichlorotetrafluoroethane; 1,1,2-trichloro-1,2,2 trifluoroethane,chlorotrifluorethylene, bromotrifluoromethane, andmonochlorotrifluoromethane, hexafluoroethane, sulfur hexafluoride,perfluoropropane, perfluorobutane and mixtures thereof. If the fluidcell is filled with one of this group, and with a less than atmosphericpartial pressure of nitrogen and oxygen (and preferably no nitrogen oroxygen), then any air that might leak into the club head and mix withthe incompressible fluid would, over time, tend come into contact withthe surface of the fluid cell 35 and would diffuse into the fluid cell,as the fluid cell composition may be altered to allow a slow rate ofpermeability for the atmospheric gases, while still preventing leakageof the inflatant gas. The fluid cell would thus act as a scavenger torid the incompressible fluid of undesired compressible fluid, as thecompressible fluid would undesirably tend to reduce the bias pressuresgenerated during axial motion. For scavenging of air, the fluid cellinflatant gas should preferably have a permeability relative to thefluid cell of less than 0.1 times that of air, and preferably less than0.01 times that of air.

In FIG. 4B, wherein the club head is generally indicated by numeral 202,the fluid cell is replaced with a diaphragm 37 held in place with clamp39, forming the flexible side of chamber 104. In practice, the diaphragm37 operates in the same manner as the fluid cell 35. Alternatively, asealed metal bellows may be used, and the chamber would then becompletely impermeable.

In FIG. 4C, wherein the club head is generally indicated by numeral 203,the pressure supplied by the compressible fluid in the third chamber ispartially or completely replaced by a spring 34, operating on piston 60.

Turning now to FIG. 5, the pivot shaft 11 is attached to hosel 4 bymeans of a press fit with smooth shaft 9, which may also be welded tothe hosel. The pivot shaft 11 is inserted into a through hole 110, intowhich external spine segments 24 are directly formed. A piston 74 serveswith end cap 72 to trap a compressible fluid. Extrusion of the end cap72 is prevented by snap ring 70. The club head is generally indicated bythe number 205.

In FIG. 6A, an alternative construction is shown wherein the hosel 4 isintegrated with the pivot shaft. The club head 204 is shown in thedistal or engaged position. In FIG. 6B, the club head 204 is shown inthe proximal or disengaged position. This proximal position alsofacilitates the reading the loft angle by way of the indicia 90.

Turing now to FIG. 7, yet another embodiment is shown wherein thechamber 111 acts as the first chamber, and is filled with anincompressible fluid. The motion of the plunger 76 into cup 78 as theclub head 206 is moved from the distal to the proximal position drivesfluid into the second chamber formed by the gap between piston 61 andcup 78. In this case, the third chamber constitutes the volume betweenseal 64 and seal 18, and is filled with a compressible fluid, which maycomprise a gas, or gas and liquid and/or gel mixture. Hole 80facilitates the insertion of the pivot cartridge by venting air duringinsertion. In FIG. 8, the right end view of the embodiment shown in FIG.7 is illustrated, showing strike surface 40.

Although only a few exemplary embodiments of this invention have beendescribed in detail above, those skilled in the art will readilyappreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention as defined inthe following claims. In the claims, means-plus-function clauses areintended to cover the structures described herein as performing therecited function and not only structural equivalents, but alsoequivalent structures.

I claim:
 1. A club head having an adjustable loft angle, comprising: asurface for impacting a golf ball; a pivot shaft mounted in the clubhead; toothed means for preventing rotation of the club head about saidpivot shaft; means for axially biasing said club head on said pivotshaft into a rotatably locked position relative to said pivot shaft; andmeans for generating a hydrodynamic bias pressure, said bias pressureresisting axial movement of said club head relative to said pivot shaftduring impact of the club head with said golf ball; whereby the loftangle of the club head remains unchanged during impact with said golfball.
 2. A club head having an adjustable loft angle as recited in claim1, wherein said means for generating a hydrodynamic bias pressurecomprises a first chamber having a first variable volume, a secondchamber having a second variable volume, and a restrictive fluid conduitplacing said first chamber in fluid communication with said secondchamber; said first chamber, said second chamber and said restrictivefluid conduit all filled with a substantially incompressible fluid,whereby axial motion of the club head on said pivot shaft flows saidincompressible fluid between said first chamber and said second chamber.3. A club head having an adjustable loft angle as recited in claim 2,wherein said axial motion of the club head on said pivot shaft creates apressure differential between said first chamber and said secondchamber, said pressure differential tending to resist said axial motion,and said pressure differential tending to increase as the velocity ofsaid axial motion increases.
 4. A club head having an adjustable loftangle as recited in claim 2, said means for axially biasing said clubhead on said pivot shaft comprising a spring.
 5. A club head having anadjustable loft angle as recited in claim 2, said means for axiallybiasing said club head on said pivot shaft comprising a third chamberhaving a variable volume comprising a compressible fluid under apressure greater than atmospheric, said compressible fluid urging theclub head into an non-rotatable position on said pivot shaft, and saidcompressible fluid pressurizing said incompressible fluid.
 6. A clubhead having an adjustable loft angle as recited in claim 5, said toothedmeans for preventing rotation of the club head about said pivot shaftcomprising axially aligned splines.
 7. A club head having an adjustableloft angle as recited in claim 5, said third chamber comprising a pistonslideably mounted within the club head.
 8. A club head having anadjustable loft angle as recited in claim 5, said third chamber isolatedfrom said second chamber by a flexible diaphragm.
 9. A club head havingan adjustable loft angle as recited in claim 5, said third chamberisolated from said second chamber by a flexible diaphragm wherein saidflexible diaphragm is metallic.
 10. A club head having an adjustableloft angle as recited in claim 5, said third chamber having a variablevolume comprising a flexible fluid cell having a continuous surface. 11.A club head having an adjustable loft angle as recited in claim 10, saidfluid cell enclosing a sealed volume, said fluid cell comprising apermeable elastomeric, polymeric, or rubber surface material surroundedby said incompressible fluid, said sealed volume inflated with acompressible fluid to a value greater than atmospheric, said gaseousmedium in said chambers comprising an inert, non-polar gas, said gaseousmedium comprising a partial pressure of air substantially less thanatmospheric, said surface material having characteristics of relativelylow permeability with respect to said gas to resist diffusion of saidgas from said sealed volume through said surface material, and ofrelatively high permeability with respect to air.
 12. A club head havingan adjustable loft angle as recited in claim 11, said gas comprising oneof more of the gasses selected from the group consisting ofperfluoropentane, perfluorohexane, perfluoroheptane,octafluorocyclobutane, perfluorocyclobutane, hexafluoropropylene,tetrafluoromethane, monochloropentafluoroethane,1,2-dichlorotetrafluoroethane; 1,1,2-trichloro-1,2,2 trifluoroethane,chlorotrifluorethylene, bromotrifluoromethane, andmonochlorotrifluoromethane, hexafluoroethane, sulfur hexafluoride,perfluoropropane, and perfluorobutane.
 13. A club head having anadjustable loft angle as recited in claim 12, said compressible fluidcontained within a flexible fluid cell, whereby bubbles of aircontaminating said incompressible fluid, when in contact with said fluidcell tend to diffuse into said fluid cell and are thereby scavenged fromsaid incompressible fluid.
 14. A club head having an adjustable loftangle as recited in claim 10, said flexible fluid cell comprising a gashaving a permeability through said fluid cell surface substantially lessthan that of either nitrogen or oxygen.
 15. A club head having anadjustable loft angle as recited in claim 5, said compressible fluidcomprising a gas.
 16. A club head having an adjustable loft angle asrecited in claim 15, said compressible fluid comprising one of more ofthe gasses selected from the group consisting of nitrogen, oxygen,argon, methane, ethane, propane, butane, fluoroform, neo-pentane,perfluoropentane, perfluorohexane, perfluoroheptane,octafluorocyclobutane, perfluorocyclobutane, hexafluoropropylene,tetrafluoromethane, monochloropentafluoroethane,1,2-dichlorotetrafluoroethane; 1,1,2-trichloro-1,2,2 trifluoroethane,chlorotrifluorethylene, bromotrifluoromethane, andmonochlorotrifluoromethane, hexafluoroethane, sulfur hexafluoride,perfluoropropane, and perfluorobutane.
 17. A pivot cartridge incombination with a golf club head having an adjustable loft angle,comprising: said pivot cartridge having a pivot shaft comprising anattachment extension, a first cylindrical bearing surface, a secondcylindrical surface, and at least one toothed shaft segmenttherebetween; said pivot cartridge having a bushing comprising a thirdcylindrical bearing surface and a inner surface for mounting to saidsecond cylindrical surface; said pivot cartridge having a pivot cylindercomprising a fourth cylindrical bearing surface slideably engaging saidfirst shaft bearing surface, a fifth cylindrical bearing surfaceslideably engaging said third cylindrical bearing surface, and at leastone toothed segment therebetween engageable with said at least onetoothed shaft segment, wherein said pivot cylinder is axially moveablebetween a distal and a proximal end position relative to said attachmentextension of said pivot shaft, wherein said toothed cylinder segment isdisengaged with said toothed shaft segment in said proximal position andis engaged in said distal position, and wherein said pivot shaft is notremovable from said pivot cylinder; and said head comprising a surfacefor impacting a golf ball, and a blind hole behind and substantiallyparallel to said surface, wherein said hole the pivot cartridge isinserted.
 18. A pivot cartridge in combination with golf club headhaving an adjustable loft angle as recited in claim 17, furthercomprising: said pivot cartridge having a first seal sealing betweensaid first cylindrical bearing surface of said pivot shaft and saidfourth cylindrical bearing surface of said pivot cylinder; said pivotcartridge having a second seal sealing between said fifth cylindricalbearing surface and said third cylindrical bearing surface of saidbushing; and said pivot cartridge having an incompressible fluidsubstantially filling all the voids of the internal volume bounded bythe exterior surface of said pivot shaft, the interior surface of saidpivot cylinder, and said first and second seals.
 19. A pivot cartridgein combination with a golf club head having an adjustable loft angle asrecited in claim 18, said incompressible fluid comprising a lubricatingoil or grease.
 20. A pivot cartridge for a club head having anadjustable loft angle, comprising: a pivot shaft comprising anattachment extension, a first cylindrical bearing surface, a secondcylindrical surface, and at least one toothed shaft segmenttherebetween; a bushing having a third cylindrical bearing surface and ainner surface for mounting to said second cylindrical surface; a pivotcylinder comprising a fourth cylindrical bearing surface slideablyengaging said first shaft bearing surface, a fifth cylindrical bearingsurface slideably engaging said third cylindrical bearing surface, andat least one toothed segment therebetween engageable with said at leastone toothed shaft segment, wherein said pivot cylinder is axiallymoveable between a distal and a proximal end position relative to saidattachment extension of said pivot shaft, and wherein said at least onetoothed cylinder segment is disengaged with said at least one toothedshaft segment in said proximal position and is engaged in said distalposition; a first and second chambers within the club head containing asubstantially incompressible fluid; and at least one restrictive conduitbetween said first and second chambers, whereby axial movement of saidpivot cylinder along said pivot shaft forces fluid between said firstand second chambers.
 21. A pivot cartridge for a club head having anadjustable loft angle as recited in claim 20, said attachment extensioncomprising a hosel.
 22. A pivot cartridge for a club head having anadjustable loft angle as recited in claim 20, said attachment extensioncomprising a splined shaft for attachment to a hosel.
 23. A pivotcartridge for a club head having an adjustable loft angle as recited inclaim 22, said attachment extension comprising a threaded shaft forfastening to a hosel.
 24. A pivot cartridge for a club head having anadjustable loft angle as recited in claim 20, said incompressible fluidcomprising a lubricating oil or grease.
 25. A pivot cartridge for a clubhead having an adjustable loft angle as recited in claim 20, saidrestrictive fluid conduit comprising the clearance between said toothedcylinder segment and said toothed shaft segment.
 26. A pivot cartridgefor a club head having an adjustable loft angle as recited in claim 20,said attachment extension comprising a hosel adapted to receive a shaft.27. A golf club head having an adjustable loft angle, comprising asurface for impacting a golf ball, and a blind hole behind andsubstantially parallel to said surface, wherein said hole a pivotcartridge as recited in claim 20 is inserted.
 28. A golf club headhaving an adjustable loft angle as recited in claim 27, furthercomprising a handle shaft and a hosel connecting said handle shaft tothe club head.
 29. A golf club head with a loft angle adjustable byexternally applied compressive and twisting forces, comprising: a clubhead having a surface for striking a golf ball, said club head pivotablymounted on a pivot shaft having an axis, said pivot shaft having aproximal end for mating to a hosel and a distal end extending into theclub head, the club head having a first and a second axial endorientations on said pivot shaft, said first orientation distallyoriented relative to said second orientation, said first orientationnon-rotatable relative to said pivot shaft, said second orientationrotatable relative to said pivot shaft, said pivot shaft and the clubhead creating a first variable volume therebetween, said first variablevolume substantially filled with an incompressible fluid, said club headcomprising a second variable volume substantially filled with anincompressible fluid, at least one restrictive conduit for fluidcommunication between said first variable volume and said secondvariable volume whereby fluid in said first variable volume may beflowed by the externally applied compressive force into said secondvariable volume, while said restrictive conduit preventing substantialfluid flow while striking said golf ball.
 30. A golf club head with aloft angle adjustable by externally applied compressive and twistingforce as recited in claim 29 wherein, said incompressible fluidcomprises a lubricating oil or grease.
 31. A golf club having a face forstriking a golf ball, comprising: a club head mounted on a shaft havingan axis, a hosel connecting said shaft to a handle for swinging the golfclub, a plurality of interconnected chambers within said club head, saidchambers filled with an incompressible fluid wherein at least two ofsaid plurality of interconnected chambers have volumes that vary withaxial motion of said head on said shaft, whereby said incompressiblefluid is driven from one of said interconnected chambers having avariable volume into another said interconnected chamber having avariable volume to produce an axially directed force resisting saidaxial motion.
 32. A golf club having a face for striking a golf ball asrecited in claim 31, said incompressible fluid comprising a lubricatingoil or grease.